The present invention relates generally to electron beam lithography, and more particularly to electron beam lithography for transferring a complicated repetitive pattern at a time by emitting an electron beam through one group among a plurality of groups of openings in a collective-exposure shaping diaphragm.
For decreasing frequency of replacing shaping diaphragms, prolonging their life and increasing processing speed at the time electron beam lithography is implemented, recent electron beam lithography apparatuses are arranged so that the electron beam shaped by a rectangle forming diaphragm is emitted through one group of elemental openings among a plurality of groups of them in a collective-exposure shaping diaphragm to transfer a complicated repetitive pattern at a time as in the case of a memory cell.
In the method of collectively transferring such a pattern through the group of elemental openings, mechanical moving and positioning mechanisms have been used to select a desired group of elemental openings by moving the collective-exposure shaping diaphragm because of a narrow range in which the electron beam passed through the rectangle forming diaphragm deflects. The electron beam generated by an electron beam source is formed into an image on the collective-exposure shaping diaphragm and the image thus formed is passed through the group of elemental openings in the collective-exposure shaping diaphragm. As a result, the configuration of the beam passed through the collective-exposure shaping diaphragm changes with the group of elemental openings.
Given that desired positioning accuracy on the surface of a workpiece is x and that a beam reduction ratio from the collective-exposure shaping diaphragm up to the surface of the workpiece is M, the positioning accuracy X of the diaphragm moving mechanism becomes x/M.
In the prior art, the collective-exposure shaping diaphragm is moved by mechanically driving the diaphragm moving mechanism. Consequently, an error x in positioning the group of elemental openings on the surface of the workpiece is settled within a predetermined range by holding the accuracy in a predetermined range.
With the prior art arrangement above, however, it has hardly been possible to satisfactorily minimize the positioning error X.
In other words, the mechanical control accuracy needs improving in conformity with the desired positioning accuracy x on the workpiece and this practice has been unpractical because the mechanical mechanism tends to become too complicated. Moreover, the position of the group of elemental openings has necessitated being precisely detected.
In a case where a diaphragm as a replacement has a setting error, where the group of elemental openings are irregularly arranged or the like, the arrangement and positions of such openings will have to be detected. Therefore, there arise problems including making the mechanical mechanism complicated and increasing the positioning time required.